Door trim panels in motor vehicles are conventionally comprised of a paper board base which is covered with a vinyl or cloth cover material. Apertures are provided in the paper board base for receiving the threaded head of a conventional plastic fastener. Such a fastener has a plurality of conical barbs which are pressed into apertures of the steel door inner panel to attach the trim panel to the door.
An alternate and desirable door inner trim panel construction would be the substitution of a molded foam base for the paper board base. In such a door trim panel construction the cover material would be placed in the mold and then the foam would be injected between the cover material and a mold portion spaced from the cover material at a distance providing the desired thickness of the foam base.
A disadvantage of such a molded foam base is that the foam material does not provide a suitable anchorage for the threaded head of the conventional fastener. Accordingly, it has been recognized as necessary and desirable to embed a plastic retainer in the foam base so that the fastener can be mounted on the retainer. Such a retainer is advantageously of injection molded plastic and has an opening in the face thereof through which the threaded head enters a hollow center. In order to mold such a hollow into the retainer, the retainer must be designed to have an open end through which the mold core defining the hollow may be withdrawn. According to the prior art, the retainer must have a closure member which obstructs the core withdrawal open end so that the molding material cannot fill the hollow of the retainer during the molding of the base.
The present invention provides a method by which a previously molded hollow plastic retainer may be embedded in the molded door trim panel without necessity of a closure member to block flow of molding material into the mold core withdrawal opening.